Simple Theremin

A recent request that caught my eye, a fairly simple theremin project. I've always found these to be neat with tons of possibilities when combined with other effects. The project was posted over on Instructables.

Original without Regulator

With Regulator

Micro POG Dual Control [modification]

Hahafender on the forum sent some pictures of the guts of his Micro Pog and wondered how This1sMyne and JHS do their dual control mods, hoping to do similar, preferably like This1sMyne with external controls.  We knew from gut shots of the mod that a 4PDT stomp is used, one pole of which is for the LED indication, and so only one pole is used for each pot.

After some probing we knew that lug 1 of all the pots connect to ground and that each control increases its own effect as the pot is rotated clockwise.  The original used 5K linear pots for all the controls, and so if we use 10K for all the pots instead (also replacing the existing pots), keep lug 3 common and just switch the wipers, then we know that the entire value of the pot out of circuit will always be in parallel with the pot in circuit and so we get a predictable affect irrespective of the position of the out of circuit pot.  2 x 10K is the 5K used in the original.  This will alter the taper and so reverse log will be the best choice [see discussion below].

For indication with the 4th pole I've shown a bi-colour LED with a common anode so that you will get a different colour for each "channel" selected.  If you're not bothered about LED indication then of course a 3PDT stomp or switch could be used instead.

Jen HF Modulator / Gretsch Playboy

Now get your irons out and build it. Place your favourite fuzz in front of it and get ready for some psychedelic brain melting action. The circuit is the same in both, Jen HF Modulator and Gretsch Playboy. For this layout, i've once again swapped the transistor pinout to match your everyday devices. Original has 2N5172 general amplifier transistors in it, but 2N5088, 2N3904 and many others are very close to those in their specs. If you want to use the original ones, just mind the pinout. I've also added series polarity protection diode and pulldown resistors for in and out to prevent your circuit from popping when switched on and off.

Here's a little dcemo clip of my build:

Death By Audio Robot - modded

This was my take on the DBA Robot but with individual switching for the IC internal functions (Vibrato, Robot and any of the octave options on the fly) rather than the rotary switch used in the original.  I thought it would be more versatile to be able to control them all individually rather than be stuck with the choices dictated by the original scheme, and all the sounds will be there with the correct settings of the toggles.  The Gain control has also been taken external after a recommendation from albru80.

I think it's probably not really worth including both and up and down momentary switches on reflection as that only chooses the direction that you step through the octave choices.  So maybe removing one of those makes more sense.  I'd suggest reading through the datasheet and deciding yourself what to include.

Info about the original:

The Death by Audio Robot is the latest in a line of sonic mayhem inducing pedals from our boys in NYC. The Robot brings Death by Audio into the low-fi, bit-crushing business. This insane pedal is a lo-fi pitch transposer that produces sweet, 8-bit ring mod effects to your guitar. The Robot features four operational modes; Normal, Octave Up, Octave Down, and Arpeggiator. The Octave Up and Octave Down modes are pretty self explanatory. The Control knob, when fully clockwise, yields either octave up or down depending on the mode. When turned down, it bends the pitch of the octave down so you can dial in the exact tone you want. In Normal mode the Robot acts as a lo-fi fuzz pedal and the Control knob bends the pitch down from clockwise. The amount of fuzz can be further toyed with using the internal gain control. Now the fun part. The Death by Audio Robot also features an arpeggiator. The pitch will arpeggiate in a sequence and the Control knob will adjust the speed of the arpeggiation. It also makes a slight change in the pitch, allowing the arpeggiator to go higher. With all this fun, who needs anything else? Arpeggiation, whacky robotic nonsense, and 8-bit fuzz fun are all jam packed together in the Death by Audio Robot.